The present invention relates generally to apparatus and methods for treating vascular conditions, and more specifically, for treating hardened or fibrous vascular conditions by inflating opposing balloon segments in a sequential manner to apply stresses that facilitate treatment of the fibrous vascular condition.
Atherosclerosis and other occlusive diseases are prevalent among a significant portion of the population. The process that may lead to atherosclerosis begins with the accumulation of excess fats and cholesterol in a blood vessel. Atherosclerotic plaque forms within the walls of the vessel and may block or restrict blood flow through the vessel. The condition commonly affects the coronary arteries, the aorta, the iliofemoral arteries and the carotid arteries. Several serious consequences may result from the restricted blood flow, such as ischemic events and blood clots that may block the artery.
There are various types of athlerosclerotic plaque that may form within the vessel wall. For example, some plaque may impede flow and exhibit a calcified or fibrous nature, while other plaque may be considered “vulnerable plaque.” Furthermore, the distribution of atherosclerotic plaque in coronary arteries can have a concentric or eccentric cross-sectional luminal shape.
While vulnerable plaque may develop within the arterial walls without generally narrowing the arterial lumen substantially, occlusive lesions may include calcified or fibrous plaque comprising, for example, necrotic tissue. The necrotic tissue associated with fibrous plaque may cause the arterial wall to progressively weaken, and a rupture of the intima can occur, thereby causing aneurysm and hemorrhage.
Various procedures are known for treating stenoses in the arterial vasculature, such as balloon angioplasty and stenting. During a balloon angioplasty procedure, a catheter having a deflated balloon attached thereto is inserted into a patient's vessel. Once positioned across a constricting lesion, the balloon is then inflated to widen the lumen to partially or fully restore patency to the vessel. After satisfactory widening of the stenosis has been achieved, the balloon is deflated. The catheter then is retracted and removed from the patient's vessel with the balloon in the deflated state. Stenting involves the insertion of a usually tubular member into a vessel, and may be used alone or in conjunction with an angioplasty procedure.
Various problems exist with the use of a conventional balloon catheter having one balloon when treating a fibrous or calcified vascular occlusion. First, a balloon catheter having a single balloon applies radially outward forces in all directions against the occlusion, and while this imposes a radially uniform pressure against the lesion, it may not be effective against treating a hardened or calcified lesion. Moreover, if the fibrous lesion is eccentric, a single balloon cannot direct forces locally against the occluding portion of the lesion.
In view of the foregoing, there is a need for apparatus and methods that effectively treat a vascular condition by applying stresses that facilitate treatment of the vascular condition, and in particular, for hardened or fibrous lesions.